An active device utilized integrated in the measurement of capacitance of a device is often limited with regard to the voltage it can be exposed to while conducting the measurement. The voltage limit can be due to a terminal or breakdown voltage that prevents the active device from receiving any voltages above the breakdown voltage without leaking significant current and dramatically reducing the life of the active device. Usual breakdown voltages in modern technologies can be in the range of 1 V to 10 V.
A high voltage device is generally a device that can operate under a voltage greater than the breakdown voltage of the active device. A capacitive microelectromechanical system (MEMS) device is an example of such a high voltage device. A capactive MEMS device facilitates the movement of elements by an applied voltage. The amount of movement does affect the capacitance of the capacitive MEMS device. Measurement of the capacitance of the capacitive MEMS device is difficult with a traditional capacitive measurement circuit circuit because the voltage required to move the elements a certain amount is often greater than the breakdown voltage of the active device of the traditional capacitive measurement circuit.
Traditional capacitance measurements are performed by connecting the high voltage device to a circuit, including the active device. However, this connection can significantly limit the voltage that can be applied to the high voltage device or can significantly limit the sensitivity of the circuit that facilitates the measurement. In fact, when the voltage applied to the device is higher than the breakdown voltage of the active device (as in the case of capacitive MEMS devices), the measurement of the capacitance of the high voltage device becomes impossible.